In this section we develop a detailed model
of the running time performance of C++ programs.
The model developed is independent of the underlying
hardware and system software.
Rather than analyze the performance of a particular,
arbitrarily chosen physical machine,
we consider the implementation of the C++ programming language
as a kind a ``virtual C++ machine'' (see Figure ).

A direct consequence of this approach is that we lose some fidelity--the resulting model will not be able to accurately predict the
performance of all possible hardware/software systems.
On the other hand, we shall see that the resulting model
is still rather complex and rich in detail.